Liquid cyclones have been used for many years for the treatment of liquid suspensions of particulate materials to separate the suspended particles on the basis of their respective specific gravities. Paper making stock is typical of the particulate suspensions which are substantially always subjected to such treatment, often in multiple stages in a series of liquid cyclones or centrifugal cleaners constructed and sized to provide progressively finer and more precise cleaning operations.
A typical cyclone for the relatively coarse cleaning of paper making stock which was developed by applicant's assignee in the early 1950's is shown in U.S. Pat. No. 2,645,346 of 1953 to Staege et al. A centrifugal cleaner for fine cleaning developed more recently by applicant's assignee is shown in U.S. Pat. No. 4,155,839 of 1979 to Seifert et al.
The various forms of apparatus shown in these and many other patents all have the common characteristic that their dimension in the direction in which the suspension flows therethrough is relatively large with respect to their cross sectional dimension. For example, a centrifugal cleaner as small as 3 inches in internal diameter--which is a size widely used in the fine cleaning of paper making stock--has a length of the order of 36 inches, while a liquid cyclone having an inner diameter of 8 inches commonly measures approximately 7 ft. in height not including the reject outlet assembly and its related control valve structure. Large liquid cyclones are correspondingly even larger, e.g. a cyclone having an inner diameter of 20 inches may have an overall height in excess of 13 ft.